1210021 has 2 divisors, whose sum is σ = 1210022. Its totient is φ = 1210020.
The previous prime is 1210019. The next prime is 1210037. The reversal of 1210021 is 1200121.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 1179396 + 30625 = 1086^2 + 175^2 .
It is a cyclic number.
It is not a de Polignac number, because 1210021 - 21 = 1210019 is a prime.
Together with 1210019, it forms a pair of twin primes.
It is a junction number, because it is equal to n+sod(n) for n = 1209986 and 1210013.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (1210051) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605010 + 605011.
It is an arithmetic number, because the mean of its divisors is an integer number (605011).
21210021 is an apocalyptic number.
It is an amenable number.
1210021 is a deficient number, since it is larger than the sum of its proper divisors (1).
1210021 is an equidigital number, since it uses as much as digits as its factorization.
1210021 is an odious number, because the sum of its binary digits is odd.
The product of its (nonzero) digits is 4, while the sum is 7.
The square root of 1210021 is about 1100.0095454131. The cubic root of 1210021 is about 106.5608401372.
Adding to 1210021 its reverse (1200121), we get a palindrome (2410142).
It can be divided in two parts, 12100 and 21, that added together give a palindrome (12121).
The spelling of 1210021 in words is "one million, two hundred ten thousand, twenty-one".
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